1. Field of the Invention
The present invention relates to a surveying apparatus which irradiates illumination light such as an infrared ray or measurement light toward a reflector to carry out ranging and/or measurement of angle relative to the reflector on the basis of the illumination light reflected by the reflector.
2. Description of the Related Art
Heretofore, there has been known a surveying apparatus having an irradiation unit provided with an objective lens for irradiating an infrared ray toward a reflector and a collimation optical system unit for observing a field of view based on visible light entering through the objective lens constructing a part of a telescope, in which the collimation optical system unit is provided with a Porro prism for converting an image within the field of view which is based on a visible light flux obtained through the objective lens into an erected non-reverse image and an ocular lens part for observing the erected non-reverse image obtained through the Porro prism (for reference, see JP-A H05-322569).
In addition, there has been also known a surveying apparatus wherein an ocular lens part of a collimation optical system unit is attached with a CCD (Charge-Coupled Device) camera as an image sensor (for reference, see JP-A 2000-275044).
Moreover, there has been known a surveying apparatus capable of obtaining three-dimensional coordinates in a short time with high accuracy, by detecting presence of an object to be measured by using a camera and detecting two-dimensional coordinates of an actual size of the object on an imaging area of the camera, then measuring a distance to the object by using distance measuring means and calculating the three-dimensional coordinates of the object based on the detected two-dimensional coordinates and the distance to the object (for example, see JP-A S63-083604).
In the conventional surveying apparatus, there is a problem that a worker has to be skilled in order to find out the reflector from the background in the field of view when looking the reflector through the ocular lens.